Last raced in sportscars in 2001, when he retired to help run the family jewellery concern in Paris, which he still does today. Gregoire started racing in single-seaters in 1992 in French Formula Renault, before moving up to French Formula 3 in 1994. After a solid season in 1996, when he took 2 podium finishes, he moved up to Formula 3000 in 1997, but the three seasons he had in the category were not that successful, failing to finish in the points. Gregoire then spent two seasons in the Open Telefonica by Nissan (also called the Nissan World) Series and also had a brief spell in GT racing.